A burning feeling after semen enters the vagina is usually caused by irritation or an allergic-type reaction. Some women have sensitivity to proteins in semen, which can trigger burning, redness, or swelling soon after contact.
Another reason is that semen has a higher, more alkaline pH than the vagina. This can temporarily disrupt the vaginal environment and lead to irritation or discomfort, especially if the tissue is already sensitive. Conditions like infections or inflammation can also make the area more prone to burning during or after sex.
Burning that happens right after intercourse and improves with condom use may suggest a reaction to semen. If symptoms last for hours or days, or come with discharge, itching, or pain, other causes like vaginitis or vulvar conditions should be considered.
It is important not to self-treat without knowing the cause. A gynecologist can evaluate your symptoms, rule out infections, and check for sensitivity or allergy. Using condoms until you are evaluated can help prevent further irritation.